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homed: disable event sources before unreffing them

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C.f. 9793530228.

We'd crash when trying to access an already-deallocated object:

Thread no. 1 (7 frames)
 #2 log_assert_failed_realm at ../src/basic/log.c:844
 #3 event_inotify_data_drop at ../src/libsystemd/sd-event/sd-event.c:3035
 #4 source_dispatch at ../src/libsystemd/sd-event/sd-event.c:3250
 #5 sd_event_dispatch at ../src/libsystemd/sd-event/sd-event.c:3631
 #6 sd_event_run at ../src/libsystemd/sd-event/sd-event.c:3689
 #7 sd_event_loop at ../src/libsystemd/sd-event/sd-event.c:3711
 #8 run at ../src/home/homed.c:47

The source in question is an inotify source, and the messages are:

systemd-homed[1340]: /home/ moved or renamed, recreating watch and rescanning.
systemd-homed[1340]: Assertion '*_head == _item' failed at src/libsystemd/sd-event/sd-event.c:3035, function event_inotify_data_drop(). Aborting.

on_home_inotify() got called, then manager_watch_home(), which unrefs the
existing inotify_event_source. I assume that the source gets dispatched again
because it was still in the pending queue.

I can't reproduce the issue (timing?), but this should
fix #17824, https://bugzilla.redhat.com/show_bug.cgi?id=1899264.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2021-03-08 11:37:17 +01:00
parent 23d24b76f3
commit cf5366387b
4 changed files with 12 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/home/homed-home-bus.c
View File

@ -885,7 +885,7 @@ static int on_deferred_change(sd_event_source *s, void *userdata) {
assert(h);
h->deferred_change_event_source = sd_event_source_unref(h->deferred_change_event_source);
h->deferred_change_event_source = sd_event_source_disable_unref(h->deferred_change_event_source);
r = bus_home_path(h, &path);
if (r < 0) {

14
src/home/homed-home.c
View File

@ -188,17 +188,17 @@ Home *home_free(Home *h) {
user_record_unref(h->record);
user_record_unref(h->secret);
h->worker_event_source = sd_event_source_unref(h->worker_event_source);
h->worker_event_source = sd_event_source_disable_unref(h->worker_event_source);
safe_close(h->worker_stdout_fd);
free(h->user_name);
free(h->sysfs);
h->ref_event_source_please_suspend = sd_event_source_unref(h->ref_event_source_please_suspend);
h->ref_event_source_dont_suspend = sd_event_source_unref(h->ref_event_source_dont_suspend);
h->ref_event_source_please_suspend = sd_event_source_disable_unref(h->ref_event_source_please_suspend);
h->ref_event_source_dont_suspend = sd_event_source_disable_unref(h->ref_event_source_dont_suspend);
h->pending_operations = ordered_set_free(h->pending_operations);
h->pending_event_source = sd_event_source_unref(h->pending_event_source);
h->deferred_change_event_source = sd_event_source_unref(h->deferred_change_event_source);
h->pending_event_source = sd_event_source_disable_unref(h->pending_event_source);
h->deferred_change_event_source = sd_event_source_disable_unref(h->deferred_change_event_source);
h->current_operation = operation_unref(h->current_operation);
@ -888,7 +888,7 @@ static int home_on_worker_process(sd_event_source *s, const siginfo_t *si, void
(void) hashmap_remove_value(h->manager->homes_by_worker_pid, PID_TO_PTR(h->worker_pid), h);
h->worker_pid = 0;
h->worker_event_source = sd_event_source_unref(h->worker_event_source);
h->worker_event_source = sd_event_source_disable_unref(h->worker_event_source);
if (si->si_code != CLD_EXITED) {
assert(IN_SET(si->si_code, CLD_KILLED, CLD_DUMPED));
@ -1067,7 +1067,7 @@ static int home_start_work(Home *h, const char *verb, UserRecord *hr, UserRecord
r = hashmap_put(h->manager->homes_by_worker_pid, PID_TO_PTR(pid), h);
if (r < 0) {
h->worker_event_source = sd_event_source_unref(h->worker_event_source);
h->worker_event_source = sd_event_source_disable_unref(h->worker_event_source);
return r;
}

2
src/home/homed-manager-bus.c
View File

@ -860,7 +860,7 @@ static int on_deferred_auto_login(sd_event_source *s, void *userdata) {
assert(m);
m->deferred_auto_login_event_source = sd_event_source_unref(m->deferred_auto_login_event_source);
m->deferred_auto_login_event_source = sd_event_source_disable_unref(m->deferred_auto_login_event_source);
r = sd_bus_emit_properties_changed(
m->bus,

6
src/home/homed-manager.c
View File

@ -79,7 +79,7 @@ static void manager_watch_home(Manager *m) {
assert(m);
m->inotify_event_source = sd_event_source_unref(m->inotify_event_source);
m->inotify_event_source = sd_event_source_disable_unref(m->inotify_event_source);
m->scan_slash_home = false;
if (statfs("/home/", &sfs) < 0) {
@ -1670,7 +1670,7 @@ static int on_deferred_rescan(sd_event_source *s, void *userdata) {
assert(m);
m->deferred_rescan_event_source = sd_event_source_unref(m->deferred_rescan_event_source);
m->deferred_rescan_event_source = sd_event_source_disable_unref(m->deferred_rescan_event_source);
manager_enumerate_devices(m);
manager_enumerate_images(m);
@ -1708,7 +1708,7 @@ static int on_deferred_gc(sd_event_source *s, void *userdata) {
assert(m);
m->deferred_gc_event_source = sd_event_source_unref(m->deferred_gc_event_source);
m->deferred_gc_event_source = sd_event_source_disable_unref(m->deferred_gc_event_source);
manager_gc_images(m);
return 0;